Student Theses, Dissertations and Capstones

Document Type

Thesis - NSU Access Only

Degree Name

Master of Science (M.S.) in Dentistry

Copyright Statement

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Department

College of Dental Medicine

First Advisor

Evren Kilinc

Date of original Performance / Presentation

January 2021

Publication Date / Copyright Date

1-1-2021

Abstract

Objective: To evaluate the efficacy of clear aligners in the correction of the curve of Spee (COS) and other orthodontic parameters. Methods: 93 completed Invisalign (Align Technology, Santa Clara, CA) cases were assigned to three groups: mild COS (< 1 mm), moderate COS (1-2 mm), and severe COS (> 2 mm). The clinical characteristics were measured at baseline (T1), after the initial round of aligners (T2), and at the last refinement (Tn). The clinically-achieved changes in the measures were compared with the digitally-predicted changes for the first round of aligners (T1-T2) and up to the last refinement (T1-Tn). Measures for the pretreatment and posttreatment cephalograms were also compared. Results: The greatest accuracy for achieving a predicted change was found for crowding (T1-T2 80%; T1-Tn 90%) and overjet (T1-T2 57%; T1-Tn 74%). The lowest accuracy was found for leveling the COS (T1-T2 33%; T1-Tn 43%) and overbite in the moderate and severe COS groups (T1-T2 36%, T1-Tn 30%). When stratifying by overbite rather than COS depth, the open bite group showed much greater accuracy (T1-T2 71%, T1-Tn 92%) than the deep bite group (T1-T2 49%, T1-Tn 53%). For all groups, the occlusal analysis yielded a significant reduction in the number of ideal posterior mandibular contacts (12.4 to 5.6), in contrary to the predicted increase. There was no significant difference in the mandibular plane angle before and after treatment. Over 75% of the achieved changes occur with the initial set of aligners. Conclusion: Invisalign has higher accuracies in achieving predicted changes in overjet (T1-Tn 74%) and crowding (T1-Tn 90%) when analyzed up to the last refinement. The overbite correction for subjects with an open bite tendency (< 1 mm overbite) tends to be higher in accuracy (T1-Tn 92%) than those with deep bite tendency (T1-Tn 49%). Invisalign showed poor accuracy in correcting vertical parameters requiring intrusion, such as with deep overbites and leveling the curve of Spee with a moderate-severe depth (43%). Invisalign shows low accuracy for the occlusal contacts with a significant reduction in the number of ideal posterior contacts (12.4 to 5.6). The changes realized by Invisalign tend to occur mainly in the initial set of aligners.

Disciplines

Dentistry

Keywords

accuracy; aligner; efficacy; invisalign; outcome; predict

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